Journal of Animal Science, Vol 72, Issue 7 1842-1848, Copyright © 1994 by American Society of Animal Science

JOURNAL ARTICLE

Dietary electrolyte balance effects on performance and metabolic characteristics in growing steers

J. G. Ross, J. W. Spears and J. D. Garlich
Department of Animal Science, North Carolina State University, Raleigh 27695-7621.

The effects of dietary electrolyte balance (DEB; mEq of Na + K - Cl/100 g of DM) on performance and acid-base status of growing cattle consuming a corn silage-based diet were established using 120 Angus (n = 60) and Angus crossbred (n = 60) steers (247 +/- 2.4 kg). Treatments consisting of 0, 15, 30, or 45 mEq of DEB/100 g of DM were obtained by varying NH4Cl and NaHCO3. Average daily gain showed a linear increase (P < .05) with increased DEB for the first 28 d and a quadratic response (P < .05) for the remainder of the 84-d study. Average daily feed intake was not affected by DEB the first 28 d. However, feed intake over the entire feeding period showed a linear increase with increasing DEB (P < .01). On d 28, plasma Na, K, and Mg were not affected by DEB, whereas Ca followed a quadratic pattern (P < .10). On d 84, plasma Na and Mg decreased linearly with increasing DEB. Plasma Cl concentrations decreased linearly (P < .01) with increased DEB on d 28 and 84. On d 28 arterial blood pH and HCO3 increased linearly (P < .05) with increased DEB, whereas ionized Ca, pCO2, and pO2 were unchanged. On d 84, arterial blood pH (P < .10), HCO3 (P < .05), and ionized Ca (P < .10) increased quadratically, whereas pO2 and pCO2 were not affected by treatment. Ruminal pH increased linearly (P < .05) with increased DEB on d 28 but showed no differences on d 84. These data indicate that DEB affects performance and systemic values in growing feedlot cattle. A DEB in the range of 15 to 30 mEq seemed to provide normal homeostasis of growing steers fed a corn silage-based diet.